US 3626354 A
A polarity testing adapter for single phase three wire systems designed for polarity testing, circuit testing and low voltage detection. It features improved polarity reversing apparatus that corrects the mismating of wiring manually. The adapter means comprises a standard plug at one end, and a socket at the other end which is connected to the plug so as to reverse the wiring at the socket, having a single entry rotatable guide disc with a marker attached to the socket rotatably. Said adapter means having testing apparatus for polarity, voltage, circuits and ground fault.
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Description (OCR text may contain errors)
United States Patent [7 2] Inventor Philip M. Banner 28 Oxford Road, Massapequa, N.Y. 11758  Appl. No. 16,477  Filed Mar. 4, 1970  Patented Dec.7, 1971  POLARITY-REVERSING ADAPTER MEANS 1 Claim, 9Drawing Figs.
 U.S.Cl 339/14 R, 339/153 [5|] lnt.Cl Il0lr 3/06  Field olSearch 339/14. 32, 33, 153, I54, 155, I8
 Relerenccs Cited UNITED STATES PATENTS 1,954,375 4/1934 Blinn 339/14 R Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. Hafer Attorney-James P. Malone ABSTRACT: A polarity-reversing adapter for single-phase three-wire systems designed for supplying electric power to small boats, yachts, seaplanes, and other equipment. The adapter comprises a standard plug at one end and a socket at the other end, which is connected to the plug so as to reverse polarity at the socket.
PATENTEuntc Hem 3.626354 SHEET 1 [IF 2 INVlz'N'l'OR.
Y PHILIP M. BANNER PATENTEDUEC 71am 3525354 same 0F 2 POLARITY-REVERSING ADAPTER MEANS This invention relates to a polarity-reversing adapter for single-phase three-wire electrical systems.
More particularly, the present invention provides an improved polarity-reversing means comprising adapters, connectors, receptacles, plugs and/or testers in the interests of safety and improving equipment, reliability, with low cost, compactness and simplicity.
This type wire is generally used on AC and DC boats where one wire is the hot wire, the second wire is a current-carrying grounded wire, and the third wire is an equipment-grounding wire. The purpose of the third wire is to protect the user from shocks and to prevent stray grounds for various pieces of equipment which may create hazards or cause damage because of electrolytic effects.
This system is commonly used on boats, which creates a problem when the boat is connected to a dock power plug. Quite often, the dock power wiring or the boat wiring is a reverse polarity so that the boat plug cannot be plugged into the dock power without causing damage. The present invention provides an adapter which may be plugged into the dock power, which will reverse the polarity when the boat plug is plugged into the other end of the adapter.
in another embodiment of the adapter, which is arranged to be permanently connected to the dock plug, the adapter socket has four recesses, so that a conventional three prong plug can be plugged into it in the first and second reverse polarity positions. ln either case, it is necessary to test the polarity of the dock socket before plugging in the boat plug.
As an individual boat owner, I am constantly reminded by authoritative sources (experienced yachtsmen and qualified statements in technical publications) to keep my wires in polarity and therefore reduce electrolysis factors and corrosion that are so devastating to the metal parts of boats. You cannot ground an electricalsystem or unit to an engine or underwater appendage, particularly when shore current is used. The corrosive action is speeded up as the electric-current is increased. Electrically and chemically when two dissimilar metals are submerged in salt water, an electric current will flow from the electropositive or corroded metal towards the electronegative or protected metal.
The setting up of stray currents could be responsible for severe damage by corrosion if proper grounding of electrical sources are not done. if the return path exhibit greater resistance to current flow than a nearby parallel metallic structure, the current will leave the desired path and jump to the nearby structure and eventually return to the source of power. This current through paths that are parallel to the intended path or conduit is stray current. If it be a direct current it will cause corrosion where it leaves. if the power is alternating current, the damage will depend upon the degree of rectification in the stray current circuit, in turn afiected by the nature of oxides present on the structures.
Polarization in its simplest form is means of assuring mating of plugs and receptacles of the same rating in only the correct position. As this may cause tremendous damage or loss of safety such as improper grounding or mixed wiring setups plus electrolysis and accelerated solution phenomena (or corrosion), it becomes rather important. Life expectancy of marine equipment already suffers from too many environmental factors without causing acceleration. Galvanic corrosion is another source causing an electrolyte to become anodic with respect to another metal in contact with the same electrolyte.
In general, whether it is the potentials of wires or many other factors, it is a must to keep your wiring in polarity. My cabin cruiser was wired correctly for use at my marina. Yet, when I take trips to other places and I check their polarity, I have found that my wiring (black and white) had to be reversed. This happened at three different marinas and, furthermore, three times in three different slips at my place. Some blame it on the original electrician-others on the boat owners who change to meet their particular needs-or they say that boat builders are sometimes responsible. Whatever the cause, we need a solution. I have been involved with this problem since 1963 and finally decided to take action by making a reasonably economic article that allows AC or DC current to be reversed in a number of ways. In 1967, l was nearly killed by using an electric drill in an improperly wired setup on a boat. To determine polarity,'all are directed to the use of an inexpensive tester that will indicate this condition. Expensive polarity reversers with sophisticated electronics are economically out of reach of the 47,000,000 registered boats in the United States privately owned.
Most boats use electric heaters, cooking apparatus, radios, television sets, lights, refrigerators, AC bilge pumps, fans, electric shavers, toasters, electric drills, battery chargers, etc. on shoreline power.
ADEQUATE GROUNDING FOR SAFETY in addition to corrosion and electrolytic action, we are concerned with the welfare of the boatowner. This polarity adapter and parts ofi'er double grounding of equipment from shoreside through to the load. When an electric current leaks from its intended path, it seeks the ground by any and all paths available to it. That is why standard 1 10-125 volt AC power supplied at dockside is made up of a three-wire grounding circuit. The third wire is a green grounding conductor that provides a low-resistance path to ground for any fault currents that may develop. This wire is connected to a metal plate on the boat that is always in contact with the water, considered a natural ground.
Since the danger of shock is always present on a boat, all metal parts of the electrical system not intended to carry current (metal enclosures, conduit, frames of motors, frames of cooling appliances, metal lighting fixtures, etc.) must be grounded (connected to the green wire). For example, frayed insulation on an electrical tool may allow the bare conductor to contact the metal shell of the tool. If the tool is not equipment grounded and the user touches any exposed metal part offering a path to the water, the current will flow through his body, to the water and the ground, causing injury and possible death. Equipment grounding prevents this by providing a safe escape route to ground for the fault current.
While conventional three-wire grounding systems is essen-. tial to electrical safety, it cannot protect against tiny current leaks which are too small to activate protective devices (fuses or circuit breakers) but powerful enough to kill or injure people, damage equipment, or cause fires. Accidents of this kind are often the result of defective tools used in maintaining a boat. ln 1 second, only 30/ l ,000 of an ampere of fault current can kill a person who is grounded. Current that small isn't enough to cause fuses or circuit breakers to cut off power.
If the estimate of 5,300 boatyards in the United States is correct, one can imagine the proportion of damage and safety as it applies to both wood and steel hulls of all sizes. The same applies to seaplanes, etc. Adequate equipment grounding and correct polarity are both accomplished through use of these adapters.
Accordingly, a principal object of the invention is to provide new and improved electrical plug adapter means.
Another object of the invention is to provide new and improved electrical plug adapter means having means to reverse the polarity of electrical power.
Another object of the invention is to provide new and improved polarity-reversing adapter means for single-phase three-wire systems. 7
Another object of the invention is to provide an improved polarity-reversing mechanism intimately associated with safety and damage control, and featuring compactness, simplicity, reliability and low cost.
Another object of the invention is to provide adapter means for use on AC and DC wiring systems where a specific selection of either of two wiring choices is required.
Another object of the invention is to provide a male plug with four prongs to match the symmetric design of the fourway receptacle offering double equipment grounds. This would be important if one should corrode or break and it adds extra safety.
Another object of the invention is to provide a polarity-testing adapter. Through simple means it will economically test the hot and equipment ground wires so as to light a neon bulb or activate audible or other indicator means to denote when wires are in polarity or if a polarity reverser is needed.
In another embodiment, the two ground prongs are removable by screw-in method, making either one of the two available as needed.
In another embodiment, we have a series of receptacles for wall or dockside use with a variety of ways to accomplish reverse polarity without the adapter. This then becomes the polarity adapter.
Another object of the invention is to provide a new and improved polarity-reversing adapter for single-phase three-wire systems of the type having a hot wire, a ground current carrying wire, and an equipment-grounding wire comprising a plug having first and second current-carrying flat prongs and a third prong of irregular cross section adapted to be connected to the third equipment-grounding wire, a socket having first andsecond current-carrying recessed contacts, and a third recessed contact or irregular cross section, said first and second socket contacts being connected to said first and second prongs so as to reverse the polarity of first and second wires connected to said first and second prongs.
These and other objects of the invention will be apparent from the following specification and drawings, of which:
FIG. I is a diagrammatic view of an embodiment of the invention.
FIG. IA is a plan view of the adapter.
FIG. 2 is a detail view ofa modification of the invention.
FIGS. 3-7 show perspective views of other embodiments of the invention.
FIG. 8 shows a polarity-testing adapter.
Referring to the figures, the invention provides an adapter unit 1 having a plug end 2 and a socket end 3. The plug end has first and second flat current-carrying prongs 4 and 5, and a third prong 6 ofirregular cross section, the three prongs being spaced in a generally triangular arrangement in conventional manner. The plug 2 is adapted to be plugged into socket 7 which has corresponding recesses 4', 5', 6'.
The socket end of the adapter has first and second recessed contacts I and 11 and a third recessed contact 12 ofirregular cross section.
In the system under discussion, the third irregularly shaped prong is connected to an equipment-grounding wire which does not normally carry current. The other two wires are current-carrying wires, one of which is grounded, and the other of which is hot.
The plug 15 represents a plug on a boat cable which is adapted to be plugged into a dock power socket such as the socket 7. A problem that arises when a boat uses a strange dock is that quite frequently the polarity of the plug 7 contacts 4 and are reversed with respect to the polarity of the boat plug 15. It is, therefore, necessary for the boat operator to check the polarity of the dock socket before making any connection so as to avoid damage. Conventional polarity testers are available for this purpose. Upon making this test, it turns out that the dock socket polarity is reversed with respect to that of the boat plug. Then the boat cannot connect to that dock power without causing damage.
In order to solve this problem, the present adapter I may be inserted between the dock socket and the boat plug. In the adapter, the prong 4 is connected to the recessed contact I0 and the prong 5 is connected to the recessed Contact 11 so that if the dock power socket 7 has a different polarity from the boat plug 15, then by inserting the adapter in series, the proper connection may be made.
FIG. 2 shows a modification of the invention wherein the socket of the adapter has a fourth prong I6 which is irregularly shaped so that it will receive the plug in first and second positions, which have polarity reverse with respect to each other. In this embodiment, the recessed contact 16 is connected to the recessed contact 12. This embodiment is useful for providing a permanent connection to the dock power with each position clearly marked so that it may be used by boats having either polarity. In all instances, the polarity must be checked with a polarity tester before making any connection. If the socket of FIG. 2 is used as the dock socket, then there is no need for any adapter.
FIG. 3 shows another embodiment of the invention having a right-angle connector I, the connections being the same as shown in FIGS. 1 and 1A. The advantage of the right-angle connector is that the plug connection is protected from the weather.
FIG. 4 shows a four-way male plug having two flat prongs 20 and 21 and two irregularly shaped prongs 22 and 23. This plug could be used with the socket of FIG. 2 for reversing the polarity appearing in the socket.
FIG. 5 shows a plug having two flat prongs 23 and 24 and a pair of irregularly shaped prongs 25 and 26 which are adapted to be screwed into the body 27. With this arrangement, one of the prongs 25 or 26 may be removed, for instance, for use with a socket of the type ofsocket 7 in FIG. 1.
FIG. 6 shows a flat plate receptacle 30 adapted to receive two four-prong plugs of the type shown in FIG. I, plug 13, or the plug in FIG. 4.
FIG. 7 shows an adapter having a twist lock type plug 31 at one end which has three prongs and having permanently connected sockets 32, 33, socket 32 being a three-recess socket 32, and a four-recess socket 33 of the type shown in FIG. 2. This adapter would permit connection to a conventional twist lock socket and then the use of one or more of the other polarity-reversing adapters.
FIG. 8 shows another embodiment of the invention, a polarity-testing adapter of a type that would quickly determine how to accomplish proper wiring polarity. Its simplicity and adaptability will permit connection to the other embodiment of this invention.
FIG. 8 shows a body member 39 having one fiat prong 34 and one irregularly shaped prong 35. A neon bulb 36 or equivalent is connected across prongs 34 and 35, preferably in series with a resistor 37.
If prong 34 is connected to the hot wire, the bulb 36 will light. If prong 34 is connected to the neutral wire, bulb 36 will not light.
If the socket of FIG. 2 is being tested, the tester 39 may check with the hot and neutral connections.
The adapters and connecters may be made of plastic, rubber or other suitable insulators.
The invention has been described in connection with boat electrical systems. However, it is also applicable wherever the system is used, for instance, when using small electrical power tools and electrical appliances such as washing machines, electric pumps, AC battery generators, electric lights, radios, etc. on either AC or DC, and wherever a given polarity is required.
I. A polarity-reversing adapter for single-phase three-wire electrical systems, requiring wire continuity systems of the type having a hot wire, a ground current carrying wire, and an equipment-grounding wire comprising,
a plug having first and second current-carrying fiat prongs, and a third prong of irregular cross section adapted to be connected to the third equipment-grounding wire,
a socket having first and second current-carrying recessed contacts, and a third recessed contact of irregular cross section, said first and second socket contacts being con nected to said first and second prongs so as to reverse the polarity of first and second wires connected to said first and second prongs,
said socket having a fourth recessed contact of irregular cross section so that a standard plug having two flat prongs and a third prong ofirregular cross section may be connected to said socket in first and reverse positions for reversing the polarity.